Cavernous transformation of the portal vein (also called portal cavernoma) occurs when the native portal vein is thrombosed and myriads of collateral channels develop in the porta hepatis to bypass the occlusion.
The currently accepted theory is that it develops as a sequel of portal vein thrombosis. Cavernous transformation results from recanalization of the portal venous thrombus as well as dilatation of paracholedochal veins in an effort to bypass the portal venous obstruction. Cavernous transformation has been shown to form as early as 6 to 20 days after acute thrombosis of the portal vein. It occurs much more commonly in patients without underlying liver disease, but often leads to portal hypertension because the collateral veins are not able to adequately handle the splenic and mesenteric inflow. In cirrhosis, cavernous transformation of the portal vein is rare because stasis of portal venous flow prevents the formation of collateral channels in and around the portal venous thrombus.
Portal cavernoma is an important cause of extrahepatic portal hypertension in children or young adults in developing countries, likely due to the high incidence of neonatal umbilical sepsis and dehydration. These children may present with hematemesis due to variceal bleeding, failure to thrive, ascites or anemia and splenomegaly. Some patients develop portal biliopathy, with cholestasis caused by ischemic biliary strictures or compression of the bile ducts by the cavernoma. In adults, conditions associated with cavernous transformation of the portal vein include myeloproliferative disorders, hypercoagulable states, pancreatitis, pyelephlebitis, and Behçet syndrome. In about 30% of cases no underlying cause is found.
Cavernous transformation of the portal vein is easily diagnosed by sonography. Gray scale and color Doppler images fail to demonstrate a normal caliber portal vein in the porta hepatis. Instead, multiple serpentine channels are seen. Color and duplex Doppler confirms the presence of portal venous type flow within those tortuous channels.
|| Caption : Gray scale US of the porta hepatis.
Description : A normal portal vein is not seen. There are sepiginous anechoic structures in the porta hepatis.
1. De Gaetano AM, Lafortune M, Patriquin H, De Franco A, Aubin B,Paradis K, Cavernous transformation of the portal vein: patterns of intrahepatic and splanchnic collateral circulation detected with Doppler sonography. AJR Am J Roentgenol, 1995. 165(5): p. 1151-5.
2. Sarin SK, Agarwal SR, Extrahepatic portal vein obstruction. Semin Liver Dis, 2002. 22(1): p. 43-58.
3. Chandra R, Kapoor D, Tharakan A, Chaudhary A,Sarin SK, Portal biliopathy. J Gastroenterol Hepatol, 2001. 16(10): p. 1086-92.
4. Denninger MH, Chaït Y, Casadevall N, Hillaire S, Guillin MC, Bezeaud A et al. Cause of portal or hepatic venous thrombosis in adults: The role of multiple concurrent factors. Hepatology 2000; 31(3):587-591.